The Montreal Protocol for the protection of the ozone layer mandates the phase out of the use of chlorofluorocarbons (CFCs). Materials more “friendly” to the ozone layer such as hydrofluorocarbons (HFCs) e.g. 134a replaced chlorofluorocarbons. The latter compounds have proven to be greenhouse gases, causing global warming and could be regulated by the Kyoto Protocol on Climate Change. Replacement materials are needed which are environmentally acceptable i.e. have negligible ozone depletion potential (ODP) and acceptable low global warming potential (GWP). These material which are useful as low GWP blowing agents for thermoset and thermoplastic foams, solvents, heat transfer fluids such as in heat pumps and refrigerants include but are not limited to, 2,3,3,3-tetrafluoropropene (1234yf), 1,3,3,3-tetrafluoropropene (1234ze), 3,3,3-trifluoropropene (1243zf), 1-chloro-3,3,3-trifluoropropene (1233zd), 2-chloro-3,3,3 trifluoropropene (1233xf). The process of manufacturing these materials typically involves processes of fluorination with HF of chloroolefins starting materials such as 1,1,2,3-tetrachloropropene (1230xa) for manufacturing 1234yf and/or 1233xf, 1,1,3,3-tetrachloropropene (1230za) for manufacturing 1234ze and /or 1233zd and 1,1,3-trichloropropene (1240za) for manufacturing 1243zf.
The present invention is directed towards a method of purification of chloroolefins having 3 carbons and a method to provide stable compositions of purified chloroolefins having 3 carbons such as 1,1,2,3-tetrachloropropene, 1,1,3,3-tetrachloropropene, 1,1,3-trichloropropene and mixtures thereof.
A first aspect of this invention includes a method of purification of chloroolefins having 3 carbons to provide chloroolefins free of decomposition product such as phosgene or phosgene precursors. Such phosgene free products can be stored in non-ferrous containers in the absence of oxygenated compounds without the need of stabilizing additives.
In a second aspect the present invention is directed towards a method of providing stable composition of chloroolefins having 3 carbons that do not appreciably decompose during storage or during their subsequent use.
In all aspects of this invention, the chloroolefins provided by the method of the present invention can be used in fluorination processes for the manufacture of Low GWP materials such as 2,3,3,3-tetrafluoropropene and 2-chloro-3,3,3-trifluoropropene from 1230xa, 1,3,3,3-tetrafluoropropene and the manufacture of 1-chloro-3,3,3-trifluoropropene from 1230za and the manufacture of 3,3,3-trifluoropropene from 1240za.
WO2009003165 discloses the stabilization of hydrofluoroolefins FIFO and/or hydrochlorofluoroolefins HCFO against degradation during storage, handling and use such by adding stabilizer(s) selected from free radical scavengers, acid scavengers, oxygen scavengers, polymerization inhibitors and mixtures thereof. U.S. Pat. No. 5,169,995 hydrochlorofluorocarbon HCFC 141b which is inhibited against decomposition with additives such as alpha-methylstyrene. U.S. Pat. No. 5,221,697 discloses the use of alumina to stabilize hydrochlorofluorocarbon HCFC 141b against decomposition during storage or use.
WO2008127940 describes the stabilization of tetrachloropropenes using an antioxidants such as a phenolic antioxidant including p.methoxyphenol or p.tert.amylphenol. The inhibitors are solid materials that makes handling on a commercial scale difficult to implement. Furthermore these inhibitors require the use of MONEL® alloy for the vessels to minimize the formation of acid or phosgene.